Validity of a Test

Classroom testing is a procedure to measure the performance or academic achievements of students. The following sections contain a detailed discussion on the characteristics of a good test. Among the five characteristics such as validity, reliability, practicality, objectivity, and interpretability, validity is explained in the given article.

Validity is the degree to which it measures what it is intended to measure. It is always concerned with the specific use of the results and the appropriateness of interpretation of test scores (Swain, Pradhan & Khatoi, 2000). For example, in a test, students were asked to write the advantages of heat to measure students’ knowledge about the importance of energy. The students got good marks but the test did not measure the students’ knowledge about the importance of different types of energy. This means the test results or interpretation of scores had low validity. According to Linn and Gronlund (2000), the adequacy and correctness of the interpretation of test scores and uses of assessment results are known as validity.

For example, two articles of ten pages by the same writer, one written in 1982 and another written in 2002 on facilities for students provided by science. In this case, the article written in 2002 is more valid than the article written in 1982.

Nature of validity

Validity refers to the rightness of the interpretation of the results of a test for a given group of

learners not the test for itself. It is a matter of degree, which means that it does not exist on an all or non-basis or totally valid or invalid but is expressed in categories to specify degrees such as high validity, moderate validity, or low validity. No test is valid for all purposes. Validity is always specific to a particular interpretation of scores or use of results. 

There is no type of validity because it is a unitary concept based on various kinds of evidence. Construct, content, criterion-related relationships are considerations during finding the degree of validity of a test. Validity involves overall evaluative judgment that requires an evaluation of how the results of a test have been interpreted and used.  It also needs the types of evidence which are provided to justify the interpretation of scores and uses of results Linn &Gronlund, 2000; Swain et al, 2000).

Functions of validity     

                                                                         

The validity of test results and interpretation of its scores perform various functions in testing and evaluation programs in educational institutions. Linn and Gronlund (2000) state the following functions of validity.

·         Validity of a test ensures the attainments of objectives formulated by the tester for the test. For example, a teacher wants to see the degree of understanding mechanics part in secondary school physics among the students, a valid test provides accurate information about students’ degrees of understanding in mechanics part of physics.

·         It identifies strengths and weaknesses among the students regarding mastery of content taught during the teaching and learning process. For example in the above-mentioned example of understanding mechanics part, if the test results are valid then students’ strengths and weaknesses in understanding the content of mechanics in physics will be appropriately found.

·         Validity of a test helps the teacher to communicate the true picture of students’ achievement during an academic session to the parents and students and plan sound activities for enhancing students’ achievements.

·         To predict truly about professions and future careers of the students, the validity of a test performs the key role in such decision making. 

·         Validity of data collection instruments is one of the important characteristics that guarantee the effective teaching and learning process.